It is long since natural colors were superseded by synthetic dyes but as "Kusaki-zome" or herbal dyeing can produce dyed articles with unique quiet, exquisite and subtle sheen and handle, natural colors have again been receiving due respect in recent years which are epitomized by general trends towards favoring naturalness.
The term "herbal dyeing" inherently means dyeing with plant-derived coloring matters. While, actually, a great majority of natural colors are of vegetable origin, a broad class of colors including animal dyes, such as cochineal and purple of the ancients (secretions of Murex brandaris, a sea snail) and mineral dyes, such as Berlin (Prussian) blue, is sometimes referred to as herbal dyes.
The natural colors applicable to herbal dyeing include coloring matters available from a large variety of plants such as Gardenia jasminoides (gardenia), Curcuma longa (turmeric), Phellodendron amurense (amur cork tree), Sagina japonica, Polygonum tinctorium, Carthamus tinctorius (safflower), Sophora japonica (Japanese pogada tree), Uncaria gambir (gambir), Prunus mume (Japanese apricot), cherry tree, Punica granatum (pomegranate), Thea sinensis (tea), Ternstoremia gymnanthera (evergreen tree), Rubia cordifolia (madder), Caesal pinia sappan (sappan wood), lithospermum, Rhus javanica (Japanese sumac), Eurya japonica, Artemisia princeps (wormwood), Miscanthus sinensis (eulalia), Chrysanthemum morifolium var. sinense (Chinese chrysanthemum), Nandia domestica. Mahonia japonica (Japanese mahonia), Pueraria lobata (kudzu-vine), Quercus acutissima (kind of oak), Quercus myrsinaefolia (bambooleafed oak), Geranium thunbergii (cranesbill), Rodgersia podophylla, Myrica rubra (bayberry), Juglans mandshurica (walnut), Haematoxylon campechianum (log wood), Quercus dentata (Daimyo oak), morning glory, Rosa hydrida (rose), Crocus sativus (saffron), Tagetes patula, Vitis coignetiae (glory vine), eggplant, acorn, Miscanthus tinctorius (eulalia), azalea, Coptis japonica (goldthread), Rosa rugosa (Japanese rose), Cryptomeria japonica (Japanese red cedar), Chamaecyparis obtusa (hinoki cypress), pine, Osmanthus heterophyllus, Prunus persica (peach tree), Houttuynia cordata, Lespedeza bicolor var. japonica (bush clover), Japanese persimmon tree, Castanea crenata (Japanese chetnut tree), Phaseous angularis, Glycine max, Rhus succedanea (wax tree), Solidago altissima (tall golden-rod), Allium cepa (onion), Taxus cuspidata (Japanese yew), Alnus japonica (Japanese alder), Pieris japonica (Japanese andromeda), Albizzia julibrissin (silk flower), etc.
Several proposals have also been made concerning the use of fungi and other microorganisms, algae, etc. or their metabolic products as dyestuffs.
Japanese Patent Kokai Publication No. 234988/1990 discloses a dyeing process employing shiitake (a variety of mushroom, Cortinellus shiitake) which comprises boiling shiitake to extract a color principle, dyeing a fabric with the extract and developing and fixing the color with a mordant. This process is described as "piece mordant dyeing" method employing an infusion of wood ash as the mordant.
Japanese Patent Kokai Publication No. 132886/1989 describes a method of dyeing a textile article which comprises dispersing a microfine powder of quartz porphyry in a water-soluble acrylic resin solution, pouring the dispersion in hot water, adding a plant extract and a dyestuff thereto, dipping a substrate textile product in the resulting dye bath and carrying out the usual after-treatments such as soaping and drying.
While this technology is intended to enhance the warmth-retaining property of textile products by taking advantage of the far-infrared light emission from quartz porphyry, the invention claims such additional functions as further warmth retention, cold retention and mothproofing through the concomitant use of a plant extract. As plant extracts for warmth retention, garlic, Chinese pepper, polypore, Kasi, Euchresta japonica, Bandai kinori, Bandai udo, polygonum fruit, comfrey, Chinese matrimony vine fruit, aloe leaf, chrolera, etc. are employed. For cold retention, citrus plants such as mandarin orange, orange, etc. are used. When mothproofing is the objective, the barks and leaves of hinoki cypress and other trees are employed. However, plant extracts are not used as dyes, and as dyestuffs, natural colors (those used in herbal dyeing) and synthetic dyes are additionally employed.
An article in the May 22, 1991 issue of the Nikkei Sangyo Shinbun covered a method of dyeing silk which comprises cutting the stalk of reishi (Ganoderma lucidum), a bracket fungus of the genus Ganoderma, into fine fragments, boiling them to prepare an extract, bottoming a woven fabric with this extract, then coloring it with a man-made dyestuff and finally dusting spores of reishi thereon.
The conventional herbal dyeing is not only complicated in dyeing procedure but inferior in dye reception and color fastness, particularly in the case of cotton and linen, so that the unique characteristic of the coloring substance is not lasting and this has been the greatest shortcoming of herbal dyeing.
Moreover, although herbal dyeing is just in line with the current general trend towards favoring naturalness, it has the limit of being not necessarily conducive to development of new functions. In this respect, the shiitake dyeing described in Japanese Patent Kokai Publication No. 234988/1990 deserves attention only in that as an uncommon kind of coloring material is used for herbal dyeing. Unless a dyeing method leads to development of a new function, it is not different from dyeing with a synthetic dyestuff.
The dyeing process proposed by Japanese Patent Kokai Publication No. 132886/1989 comprises adding quartz porphyry and a plant extract to a synthetic dye bath to exploit the warmth-retaining feature of the far-infrared light emission from quartz porphyry and the warmth-and-cold retaining and mothproofing actions of the plant extract but inevitably the deposit of quartz porphyry on the textile article detracts from its handle and when a natural color is used as the dyestuff, the fastness of the color obtainable is not satisfactory.
In the technology reported in the May 22, 1991 issue of the Nikkie Sangyo Shinbun, bottoming is performed with reishi but the bottoming is a pretreatment and the actual is dyeing performed with a man-made dyestuff. The above article says, "Reishi builds up colors, viz. blue, red, yellow and purple" and "the stalk of reishi is cut into fine fragments and boiled to prepare an extract". However, although reishi occurs in six kinds, namely, seishi (blue), sekishi (red), ooshi (yellow), hakushi (white), kokushi (black) and shishi (purple), it is not true that reishi builds up colors and, moreover, they use the stalk (stipe) which is less useful than the "cap (pileus)" which is rich in activity. Thus, both factually and technically, there are several doubtful points. After all, the dyed product mentioned in this article is not a product dyed with reishi to reproduce "the color of reishi" but nothing more than a woven fabric given a deluxe feeling by pretreatment with an extract of the stalk of reishi or dusting with spores of the fungus.
The present invention has been developed, against the above background, to provide a dyed textile article having the natural and unique hue and feeling of reishi, with sufficient depths of color and extremely high color fastness, and even having antimicrobial and antiallergic activities.